Description: Thallus crustose to subleprose, episubstratic, greyish white, sometimes pale brown- or rose-tinged, composed of irregular to somewhat flattened aggregations of soredia and hyphae heavily incrusted by crystals, forming up to 5 mm thick and to 1 cm wide, soft, cottony, convex cushions; prothallus visible only in young, thinner thalli, usually whitish to pale brown. Medulla of colourless hyphae densely covered in plate-like crystals visible under polarized light. Apothecia and pycnidia not known. Photobiont trentepohlioid. Spot tests: thallus K-, C-, KC-, P-; medulla and soralia UV+ pale blue. Chemistry: lepraric acid (major), plus variable amounts of roccellic acid, and ‘latebrarum unknown’.
Note: a mainly temperate species found beneath underhangs and in crevices of siliceous rocks which are seldom wetted by rain, much more rarely on old trunks of Quercus.
Growth form: Leprose
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)